If the client-server communications break, you can quickly restore communications by replacing the Sylink.xml file on the client computer. You can replace the Sylink.xml file by deploying a communication update package. Use this method for a large number of computers, for the computers that you cannot physically access easily, or the computers that require administrative access.
Communication Update Package Deployment is available as of version 12.1.2. For earlier versions, you can use alternate methods to replace the Sylink.xml file.
To restore client-server communication settings with Communication Update Package Deployment
In the console, on the Home page, launch the Client Deployment Wizard.
Click Help > Getting Started Page and then under Required tasks, click Install the client software on your computers.
For 12.1.x, in the Common Tasks menu, click Install a client.
In the Client Deployment Wizard, under Communication Update Package Deployment, select whether you want a package for Windows or Mac clients, and then click Next.
Select the group on which you want to apply the policy, and then click Next.
For Windows clients only, you can set password protection.
Choose one of the following deployment methods, and then click Next:
After the communication update package is applied, confirm that the computers successfully communicate with Symantec Endpoint Protection Manager.